The present invention relates generally to automatic performance devices such as sequencers or automatic rhythm performance devices, and more particularly to an automatic performance device having a timing modifying function which allows tone generation timing to be easily varied during an automatic performance to thereby impart a variety of musical expressions to the performance.
The prior art automatic performance devices are designed to generate tones at predetermined timing by sequentially reading out performance data that are prestored in order of performance. In contrast, music performance by a human player presents different musical expressions every time even when the performance is made plural times on a same sheet of music, because the player's emotion may considerably change with the progress of the performance or may be substantially affected by the audience' reaction. However, although the prior art automatic performance devices can quite accurately reproduce the recorded performance data every time in much the same way as playing back of records, they can only provide a monotonous performance lacking musical variety due to the fact that they are unable to impart "on-the-spot" emotional expressions as in a live performance.
As one example of a technique for imparting musical variety to an automatic performance, Japanese Patent Laid-open Publication No. SHO 62-183496 discloses providing "fluctuation" by fluctuating tempo clock in a random manner. But, this technique alone still has the problem that it can only impart monotonous and uniform variation to an automatic performance.
Further, there has recently been proposed an automatic performance device which permits a human performance by finely controlling tone generation timing of performance data to vary or stagger, as disclosed in. Japanese Patent Laid-open Publication No. HEI 5-73036. Namely, the tone generating timing of the performance data is controlled to vary during an automatic performance, on the basis of "deviation pattern data" that is prepared for each predetermined performance timing (for example, for each beat or for each clock pulse) and indicating how much the individual tone generation timing should deviate from the predetermined performance timing. However, such a prior art automatic performance device would present a problem that a great number of "deviation pattern data" are required in addition to the performance data. This device is also disadvantageous in that the tone generation timing can only vary as dictated by the deviation pattern data, thus presenting another problem that the tone generation timing varies monotonously in an uniform manner irrespective of what the original performance data may be like.